Being currently unemployed, I try to build as much of my photography equipment as possible.

I created the pictured arm to allow me to attach my tablet to my tripod in order to control my camera while outdoors.

There's a 3/8" conduit hanger fastened to a tripod leg, into which a knob with a fixed 3/8" bolt is screwed, passing through a 1/2" piece of PVC.

I imagined that there would be rotation, so in addition to metal washers, I used neoprene washers for friction. This is not working.

How can I keep the arm from rotating downward when the knob is tightened down. I bought a variety of alternative parts in case there were issues.

Any help would be appreciated.

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If the relation (distance to) to the tripod head will remain fixed, cut in a PVC Wye fitting and attach a second branch in the same manner, a little further up the tripod leg.

Good luck.

Can you explain more?

Are you speaking in terms of creating a counterweight?

I was thinking in terms of creating more friction at the rotational axis.

A short distance up the long PVC arm, cut in a 45 degree tee (Wye) fitting and run another branch from that tee back to another clamp on the tripod leg, anchoring it and stopping the rotation.

Ok, I understand what you're saying now.

The problem with that is that it allows no adjustment of angle of the arm. The only adjustment would be in the ballhead attached to the tablet holder.

If the attachment to the tripod leg is a simple clamp, and we already know the conduit clamp rotates, then loosening both clamps and shortening or lengthening the the distance to the conduit clamp on the Wye branch, will pivot the assembly along an arc from the base clamp as the Wye clamp rides up and down the tripod leg.

The Wye branch is a rigid adjustment, but perhaps if you could find the right spring weight, that would be the way to go. I just suggested PVC because you were already using it.

Think of the springs on a Balanced-arm Lamp.

Balanced-arm lamp - Wikipedia

Just to clarify, this is the kind of clamp that I'm using. There's no spring action. The clamp itself is not moving at all, the PVC is rotating around the bolt holding it to the tripod leg.

cmort:

Do you have anything besides PVC on hand to use for the arm? As I see it, the round, smooth plastic doesn't permit the knob to be tightened enough to hold the rest of the assembly in place. If you had something flat(maybe 1/8" aluminum or steel), and put a plate washer and perhaps a lock washer between the flat piece and the knob, that might provide the tension needed -depends somewhat on the weight of your tablet.

Andy


P.S. Just realized that the threaded portion of the knob assembly would be too long for what I'm suggesting -would either have to be cut to fit, or a spacer added.

Please show a closer picture of the bolt, washer area. Hard to say without seeing it. Seems you need a washer that will "dig" into the pvc or a different rubber o ring to compress tight enough.

Perhaps put a nut on the bolt, tight securely then the washer then pvc and a outer nut.

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Still Running Against the Wind

OK, got it now. You'd need a sliding PVC clamp for the Wye branch Idea. Maybe attach another one of those clamps your using for the tripod leg to the PVC and attach the two clamps together with some threaded rod.

I meant attaching a spring, or even a few long rubber bands higher on the PVC and tripod leg, higher than the current attachment point, to add some adjustable tension to your current design. Like the tension spring balanced arm on the lamp Wiki.

Maybe this style lock washer?

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Mike, AmVets Member, Navy Vet

A counterweight (or second stabilizing attachment arm) to releave the torquing force at your current attachment would go a long way towards solving your problem.
Once that is done, you could add friction at the axis point by means of a couple of friction washers.
Those might be made from fishing reel drag washers or even skate board tape epoxied to steel.
I find EEbay to be an excellet sourse of rube goldberg parts myself :-)

p.s. Be careful you on't invest so much in the chase of teh fix that the project becomes cost prohibitive for teh end result. Been there-Done that multiple times myself.

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Dave

I think I've figured out what, or more accurately, WHERE the problem is.

There's a 3/8" socket in one end of the clamp. I was screwing a knob with a fixed 3/8" bolt in it. What was happening was NOT was the PVC rotating around the bolt. It was the bolt rotating in the socket on the clamp. There's no way to "fix" that which allows adjustment.

I bought a bunch of extra parts to allow for changes based on trial and error, and that was a good idea. I have substituted a knob with a 3/8" nut in it. This allows me to FIX a 3/8" bolt in the clamp (with what I haven't decided yet, maybe my new hot glue gun, or with epoxy) so that the knob can be tightened down on the PVC. The PVC to bolt joint will be the only pivot point, and that's already been proved, since it didn't move a fraction of an inch.

I'll get the bolt secured into the clamp and try again.

Edit: Apparently Home Depot has red Loctite, so I'll try that.

Maybe some of friction tape around the PVC.

I had rubber washers snugged against the PVC when it failed.

The problem was that the 3/8" shaft on the knob was turning counter clockwise under the weight of the arm and tablet.

Last night I replaced the knob with the fixed shaft with a piece of 3/8" threaded rod and a knob with a nut set into it. I used red Loctite to hold the rod in place in the pipe clamp. I also added a star nut between the clamp and the PVC. The shaft no longer rotates in the clamp.

It still wanted to rotate loose (albeit nowhere near as much), so I just rotated the PVC arm to the right, so that the weight caused it to tighten instead. That problem appears to have been fixed now.

I now just need to fabricate pieces to hold the tablet in the carrier. I'm planning to use plexiglas pieces with holes cut in them to fit underneath the caps.

Put a nut on the 3/8" bolt and secure the nut after the bolt is in. There will be slight friction adjustment available or you can walk around with a 6" crescent wrench.

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Front sight and squeeze

I bought a clamp on bench vise and a glue gun from Harbor Freight and they paid for themselves in a couple of hours this morning.

With the vise, I was able to accurately bend a "T" mending plate a right angles to itself so that the tablet sits level.

I then glued the plate to the PVC.

I just need to make the pieces to hold the tablet in.

Take two seperate lengths of paracord. Attach one end of each to the tripod upper part and the tablet rig. Use a spring clamp to hold the two lengths together. When moving the rig, just loosen up the clamp a bit with one hand while you position the tablet with the other. Then release the clip to hold at that adjusted length.

It's just about done.

Instead of the plexiglass to hold it in, I cut 13/16" holes in the bottoms of a couple of pill bottles, then cut the bottoms off. They slip securely over the 1/2" PVC inserted into the elbows, and the caps go on top. To insert and remove the tablet, I just turn the top elbow to the side.

I'll probably try it tonight.

I don't even fully understand the question - forget about the answer - but I believe that neoprene washers are exactly what you are NOT looking for to add friction. Steel washers (ungreased) can provide friction, but it probably happens all at once. Fiber (whatever exactly that means) washers are what used to be generally used for the purpose I believe you are describing. With a little luck, you may find an old-fashioned hardware store that has all kinds of washers for literally pennies, and you can buy a few kinds and see what works.

Good luck!

I get as much stuff as I can out of the bulk/specialty drawers at Lowes and Home Depot. That's the only place where you can get knobs, threaded rod, etc. The local Ace Hardware has some stuff that neither of them does.